package DailyPractice.Day23;

import java.util.Scanner;

/**
 * @author lumin
 * @date 2022/05/20 00:01
 **/
public class N01 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str1 = sc.nextLine();
        String str2 = sc.nextLine();
        int m = Math.max(str1.length(),str2.length());
        int n = Math.min(str1.length(),str2.length());
        int k = 0;
        int[][] arr = new int[m][m];
        for (int i = 0; i < n; i++) {
            if(str1.charAt(i) != str2.charAt(i)){
                k++;
            }
        }
        System.out.println(m - n + k);
    }
}